learn it! title
 Explanation of a joke

Lisa from Taiwan asks:

Why is it funny? What does the last sentence mean?

'Taking his seat in his chambers, the judge faced the opposing lawyers. "So," he said, "I have been presented, by both of you, with a bribe."
Both lawyers squirmed uncomfortably. "You, attorney Leon, gave me $15,000. And you, attorney Campos, gave me $10,000." The judge reached into his pocket and pulled out a check. He handed it to Leon.
"Now then, I'm returning $5,000, and we're going to decide this case solely on its merits."'

Roger replies:
To decide a case 'solely on it merits' means that only the intrinsic rights and wrongs of the arguments will be considered. In a court of law one would expect all cases to be decided solely on their merits.

It is funny because that is no longer possible in this case as the judge has already pocketed bribes of $10,000 from both the defense and prosecution counsels. He argues that his judgement will be unbiased now that the amount of bribe from defense and prosecution is equal, but would you expect to get a fair trial in a court of law from a judge who was open to bribery?